The purpose of this study was to validate the open field test as a measure of anxiety-like and exploratory behavior in infant titi monkeys, and to evaluate the response to availability of attachment figures, the father (the primary attachment figure and carrier), the mother, and the oldest sibling. Infants underwent open field testing for five days at four and six months of age. In four successive five minute trials, cages containing the father, mother, sibling, or an empty cage were rotated on one side of the testing apparatus. It was hypothesized that infants would emit the highest number of separation vocalizations in response to the father and that intensity of response would correlate with parental care from 0-3 months. Preliminary analyses (n=9 infants) revealed significant individual differences (p <0.0001), and indicated an effect of condition (p<0.0001) and a sex by condition interaction (p = 0.015). Infants vocalized more with access to the father and oldest sibling compared to the mother. Females vocalized more than males in both parent conditions and both sexes vocalized less in response to the empty cage. Paternal carrying duration from 0-3 months correlated with decreased vocalizations in the empty condition. These preliminary findings suggest that infants differentially vocalize in a novel situation dependent on availability of an attachment figure, and suggest that higher paternal carrying leads to lower anxiety later.